Residential and commercial power distribution comprising AC power mains are typically optimized for efficiency of power distribution at the particular frequency, voltage and current of the end user in the particular power service area. As important is the need for flexibility to provide the various combinations of voltage and power for differing end users who may be juxtaposed. The typical U.S. distribution systems provide a three-phase “medium” voltage (10-30 KV) pole-to-pole line to which a first step-down to 480 V 3 phase for a drop to the large/commercial building is typically provided by pole transformers. In the building, the voltage is typically further dropped to 120/208 (3-phase) and distributed to neighboring and/or adjoining users, or alternately first distributed at 480V to neighboring users and the subsequently reduced to 120/208.
Increasingly for contemporary business and residential users, a separately wired data infrastructure is unattractive, inflexible or simply unavailable, and data over the power line (power mains) becomes interesting. However, blocks to effective power mains data transfer are the facility transformers, particularly the 3-phase 480-to-120/208 transformers that are used to provide the necessary voltage step-down. Furthermore, the final (480-to-120/208) step-down also often transforms the power distribution from 3-phase “Δ” (or “Y”) format to 3-phase “Y” format, which further complicates data transfer on the power mains through the transformer.